books.google.com - The report describes a procedure that was used by American National Standards Institute (ANSI) Subcommittee to establish working stresses for various species of wood used for ladder parts. Such parts are made from high quality, essentially clear wood for a product that requires a high level of safety....https://books.google.com/books/about/Allowable_bending_stresses_of_wood_for_u.html?id=5udaYvI5KrUC&utm_source=gb-gplus-shareAllowable bending stresses of wood for use in portable wood ladders

The report describes a procedure that was used by American National Standards Institute (ANSI) Subcommittee to establish working stresses for various species of wood used for ladder parts. Such parts are made from high quality, essentially clear wood for a product that requires a high level of safety. The procedures outlined here might suggest ways to arrive at working stresses for other structural members made from high quality wood.